In an air conditioner, a drain pan for receiving drain water from a heat exchanger is provided under the heat exchanger. The drain water which collects in the drain pan is discharged to the outside using the inclination of a drain pipe connected to the drain pan, or is discharged to the outside by being suctioned by a built-in drain pump. In a case where a ceiling-mounted air conditioner or the like has difficulty in naturally discharging drain water using the inclination of the drain pipe, the drain water in the drain pan can be forcibly discharged to the outside using the drain pump (see Patent Literature 1, for example).
Under the Building Sanitation Law, meanwhile, the quality of water in the drain pan has to be checked as frequently as once a month, for example.
Water quality examination check on the drain pan and the vicinity of the suction port of the drain pump requires onerous work involving many steps, because the check is performed by taking the drain pan out of the air conditioner or by detaching some outer panels from the air conditioner. Thus, the water quality examination check is laborious work, and there has been a demand for simplifying the water quality examination check.
An air conditioner of Patent Literature 1 has been known as allowing the water quality examination check. In this air conditioner, an inspection window made of a transparent plate member is provided to a side wall of the drain pan, and an opening part through which the inspection window is visible is formed in a casing of the air conditioner. This air conditioner allows the drain pan to be visually examined from the opening part via the inspection window.